Mice deficient in the nuclear hormone receptor RORγt have defective development of thymocytes, lymphoid organs, Th17 cells, and type 3 innate lymphoid cells. RORγt binds to oxysterols derived from ...cholesterol catabolism, but it is not clear whether these are its natural ligands. Here, we show that sterol lipids are necessary and sufficient to drive RORγt-dependent transcription. We combined overexpression, RNAi, and genetic deletion of metabolic enzymes to study RORγ-dependent transcription. Our results are consistent with the RORγt ligand(s) being a cholesterol biosynthetic intermediate (CBI) downstream of lanosterol and upstream of zymosterol. Analysis of lipids bound to RORγ identified molecules with molecular weights consistent with CBIs. Furthermore, CBIs stabilized the RORγ ligand-binding domain and induced coactivator recruitment. Genetic deletion of metabolic enzymes upstream of the RORγt-ligand(s) affected the development of lymph nodes and Th17 cells. Our data suggest that CBIs play a role in lymphocyte development potentially through regulation of RORγt.
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•Sterols are necessary and sufficient to promote RORγ transcriptional activity•RORγ promoted transcription maps into the cholesterol biosynthetic pathway (CBP)•In the CBP, the RORγ ligand is downstream of lanosterol and upstream of zymosterol•Genetic manipulation of ligand biosynthetic enzymes affect RORγ functions in vivo
RORγt-deficient mice lack lymph nodes and Th17 cells. Santori et al. show that sterol lipids are necessary and sufficient to drive RORγt-dependent transcription and that in mammalian cells RORγt ligand is a cholesterol biosynthetic intermediate. Furthermore, genetic manipulation of RORγt-ligand biosynthesis affects development of lymph nodes and Th17 cells.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
IL-17-producing CD4⁺ T helper (Th17) cells have recently been defined as a unique subset of proinflammatory helper cells whose development depends on signaling initiated by IL-6 and TGF-β, autocrine ...activity of IL-21, activation of STAT3, and induction of the orphan nuclear receptor RORγt. The maintenance, expansion, and further differentiation of the committed Th17 cells depend on IL-1β and IL-23. IL-17 was originally found produced by circulating human CD45RO⁺ memory T cells. A recent study found that human Th17 memory cells selectively express high levels of CCR6. In this study, we report that human peripheral blood and lymphoid tissue contain a significant number of CD4⁺FOXP3⁺ T cells that express CCR6 and have the capacity to produce IL-17 upon activation. These cells coexpress FOXP3 and RORγt transcription factors. The CD4⁺FOXP3⁺CCR6⁺ IL-17-producing cells strongly inhibit the proliferation of CD4⁺ responder T cells. CD4⁺CD25high-derived T-cell clones express FOXP3, RORγt, and IL-17 and maintain their suppressive function via a cell-cell contact mechanism. We further show that human CD4⁺FOXP3⁺CCR6⁻ regulatory T (Treg) cells differentiate into IL-17 producer cells upon T-cell receptor stimulation in the presence of IL-1β, IL-2, IL-21, IL-23, and human serum. This, together with the finding that human thymus does not contain IL-17-producing Treg cells, suggests that the IL-17⁺FOXP3⁺ Treg cells are generated in the periphery. IL-17-producing Treg cells may play critical roles in antimicrobial defense, while controlling autoimmunity and inflammation.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Nuclear hormone receptors (NHRs) are transcription factors regulated by small molecules. The functions of NHRs range from development of primary and secondary lymphoid organs, to regulation of ...differentiation and function of DCs, macrophages and T cells. The human genome has 48 classic (hormone and vitamin receptors) and nonclassic (all others) NHRs; 17 nonclassic receptors are orphans, meaning that the endogenous ligand is unknown. Understanding the function of orphan NHRs requires the identification of their natural ligands. The mevalonate pathway, including its sterol and nonsterol intermediates and derivatives, is a source of ligands for many classic and nonclassic NHRs. For example, cholesterol biosynthetic intermediates (CBIs) are natural ligands for RORγ/γt. CBIs are universal endogenous metabolites in mammalian cells, and to study NHRs that bind CBIs requires ligand‐free reporters system in sterol auxotroph cells. Furthermore, RORγ/γt shows broad specificity to sterol lipids, suggesting that RORγ/γt is either a general sterol sensor or specificity is defined by an abundant endogenous ligand. Unlike other NHRs, which regulate specific metabolic pathways, there is no connection between the genetic programs induced by RORγ/γt and ligand biosynthesis. In this review, we summarize the roles of nonclassic NHRs and their potential ligands in the immune system.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The impact of nutritional status during fetal life on the overall health of adults has been recognized; however, dietary effects on the developing immune system are largely unknown. Development of ...secondary lymphoid organs occurs during embryogenesis and is considered to be developmentally programmed. Secondary lymphoid organ formation depends on a subset of type 3 innate lymphoid cells (ILC3) named lymphoid tissue inducer (LTi) cells. Here we show that mouse fetal ILC3s are controlled by cell-autonomous retinoic acid (RA) signalling in utero, which pre-sets the immune fitness in adulthood. We found that embryonic lymphoid organs contain ILC progenitors that differentiate locally into mature LTi cells. Local LTi cell differentiation was controlled by maternal retinoid intake and fetal RA signalling acting in a haematopoietic cell-autonomous manner. RA controlled LTi cell maturation upstream of the transcription factor RORγt. Accordingly, enforced expression of Rorgt restored maturation of LTi cells with impaired RA signalling, whereas RA receptors directly regulated the Rorgt locus. Finally, we established that maternal levels of dietary retinoids control the size of secondary lymphoid organs and the efficiency of immune responses in the adult offspring. Our results reveal a molecular link between maternal nutrients and the formation of immune structures required for resistance to infection in the offspring.
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DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Identification of physiological modulators of nuclear hormone receptor (NHR) activity is paramount for understanding the link between metabolism and transcriptional networks that orchestrate ...development and cellular physiology. Using libraries of metabolic enzymes alongside their substrates and products, we identify 1-deoxysphingosines as modulators of the activity of NR2F1 and 2 (COUP-TFs), which are orphan NHRs that are critical for development of the nervous system, heart, veins, and lymphatic vessels. We show that these non-canonical alanine-based sphingolipids bind to the NR2F1/2 ligand-binding domains (LBDs) and modulate their transcriptional activity in cell-based assays at physiological concentrations. Furthermore, inhibition of sphingolipid biosynthesis phenocopies NR2F1/2 deficiency in endothelium and cardiomyocytes, and increases in 1-deoxysphingosine levels activate NR2F1/2-dependent differentiation programs. Our findings suggest that 1-deoxysphingosines are physiological regulators of NR2F1/2-mediated transcription.
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•1-deoxyphingosines bind and modulate NR2F1 and NR2F2 transcriptional activity•Genetic deletion of Sptlc2 phenocopies Nr2f2 deficiency in lymphatic development•Inhibition of sphingolipid synthesis impairs human cardiomyocyte differentiation•1-deoxysphingosine supplementation promotes human cardiomyocyte maturation
Wang et al. identify 1-deoxysphingosines as modulators of COUP-TF activity. Inhibition of sphingolipid biosynthesis mimics COUP-TF knockout phenotypes in lymphatic development and in human ESC-derived cardiomyocytes, whereas elevated levels of 1-deoxysphingosines enhance cardiomyocyte differentiation. Thus, sphingolipids could be physiological ligands for COUP-TFs and could play a critical role in development.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Nuclear hormone receptors (NHRs) are a family of ligand-regulated transcription factors that control key aspects of development and physiology. The regulation of NHRs by ligands derived from ...metabolism or diet makes them excellent pharmacological targets, and the mechanistic understanding of how NHRs interact with their ligands to regulate downstream gene networks, along with the identification of ligands for orphan NHRs, could enable innovative approaches for cellular engineering, disease modeling and regenerative medicine. We review recent discoveries in the identification of physiologic ligands for NHRs. We propose new models of ligand-receptor co-evolution, the emergence of hormonal function and models of regulation of NHR specificity and activity via one-ligand and two-ligand models as well as feedback loops. Lastly, we discuss limitations on the processes for the identification of physiologic NHR ligands and emerging new methodologies that could be used to identify the natural ligands for the remaining 17 orphan NHRs in the human genome.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Autonomic parasympathetic neurons (parasymNs) control unconscious body responses, including “rest-and-digest.” ParasymN innervation is important for organ development, and parasymN dysfunction is a ...hallmark of autonomic neuropathy. However, parasymN function and dysfunction in humans are vastly understudied due to the lack of a model system. Human pluripotent stem cell (hPSC)-derived neurons can fill this void as a versatile platform. Here, we developed a differentiation paradigm detailing the derivation of functional human parasymNs from Schwann cell progenitors. We employ these neurons (1) to assess human autonomic nervous system (ANS) development, (2) to model neuropathy in the genetic disorder familial dysautonomia (FD), (3) to show parasymN dysfunction during SARS-CoV-2 infection, (4) to model the autoimmune disease Sjögren’s syndrome (SS), and (5) to show that parasymNs innervate white adipocytes (WATs) during development and promote WAT maturation. Our model system could become instrumental for future disease modeling and drug discovery studies, as well as for human developmental studies.
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•Generation of functional, SCP-derived parasymNs from hPSCs•ParasymNs and symNs mimic human ANS development•Functional defects of parasymNs are characterized in models of FD, COVID-19, and SS•Human parasymNs regulate adipose maturation and function in vitro
Wu et al. differentiate hPSC-derived Schwann cell precursors into functional parasympathetic neurons. These parasympathetic neurons are employed to study specific defects in the genetic autonomic disorder familial dysautonomia, during COVID-19 infection, and in the autoimmune disease Sjögren's syndrome. The role of parasympathetic innervation of adipose tissue development is assessed.
Dendritic cells (DC) play a crucial role in initiating immune responses to tumors. DC can efficiently present antigens from apoptotic tumor cells, but apoptotic cells are thought to lack the ...inflammatory signals required to induce DC maturation. Here, we show that apoptosis of 67NR mouse carcinoma cells via the Fas (CD95) pathway or induced by the anticancer drug bortezomib (PS‐341) but not by ultraviolet irradiation is associated with the production of maturation signals for DC. These data have important implications for the effects of chemotherapy on antitumor immunity in solid and hematologic malignancies.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Although it is clear that positive selection of T cells involves recognition of specific self-peptide/MHC complexes, the nature of these self-ligands and their relationship to the cognate antigen are ...controversial. Here we used two complementary strategies to identify naturally occurring self-peptides able to induce positive selection of T cells bearing a specific T cell receptor, OT-I. Both the bioassay- and bioinformatics-based strategies identified the same self-peptides, derived from F-actin capping protein and β-catenin. These peptides displayed charge conservation at two key TCR contact residues. The biological activity of 43 other self-peptides and of complex peptide libraries directly correlated to the extent of conservation at TCR contact residues. These results demonstrate that selecting self-peptides are rare and can be identified by homology-based search strategies.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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